Piston ring expander



' Dec. 24, 1935. 1.. M. BRANNAN 2,025,335

PISTON RING EXPANDER Filed Sept. 9, 1935 l w, M g] M,

; 6 0 'll m lh. m 9 6 J 4- 7g 12 .5 13 v I v Patented Dec. 24, 1935 UNITED STATES PATENT OFFICE PISTON RING EXPANDER Application September 9, 1935, Serial No. 39,699

11 Claims.

My invention relates to piston ring expanders for use 'with and adapted to augment the expanding action of piston rings for internal combustion engines and the like. 7 More particularly, my invention is an improvement on the piston ring expander disclosed in the copending application, Serial No. 23,477, filed May 25, 1935, by Herman Teetor. The Teetor application discloses a resilient one-piece spring expander having a thin supporting strip or band with spring leaves integrally connected by necks at their central portions to the supporting band, the necks being bent so that the leaves overly the supporting band. Demonstration has proven that this Teetor construction possesses very considerable merit as a practical and commercial device. I have found, however, that in some instances, it is desirable to provide additional spring pressure against the piston ring and to 20 distribute the strains, to which the spring leaves are subjected, more uniformly throughout the length of the leaves. Accordingly, I have provided the one-piece ring expander with sets of superimposed spring leaves, which give the de- 25 sired pressure characteristics for all sizes of rings and engines, cause the strains on the leaves to be more evenly distributed,'reduces to a minimum the possibility of breakage, and increases the efficiency of the expander. The objects of my invention will be more apparent from the following description taken in conjunction with the accompanying drawing in which:

Fig. 1 is a plan view of a portion of a stamping from which my expander is made;

Fig. 2 is a perspective view of a portion of Fig. 1 shows the stamping from which the expander is made and which is composed of a thin ribbon of soft steel. As indicated, the stamping is cut to provide a supporting strip or band 5 having a width approximately equal to the width of the ring groove in the piston and of a length slightly less than the circumference of the ring groove at its minimum diameter. The stamping is further out to provide the leaves 6 and 1, the top leaves 6 being integrally connected to the upper edge of the band 5 by the necks 8 and the leaves I being integrally connected to the lower edge of the band 5 by the necks 9. 5 The leaves 6 are of substantially the same width as the supporting band while the leaves I are narrower and shorter than the leaves 6. After the stamping is formed the leaves 6 and I are curved or bowed as illustrated in Fig. 2. Then 10 the necks 9 are bent to place the central portions of the leaves 1 flat against the supporting band (Figs. 2 and 3). The necks 8 are next bent to place the leaves 6 in superimposed position over. and in firm engagement with the 15 leaves 1.

Referring to Fig. 1, it will be observed that the holes or openings II) at the sides of the necks 8 are formed so that the lower edges of the leaves 6 are tangential with the holes. Thus the holes do not extend up into the leaves but extend down into the top edge of the band 5 and the holes do not weaken the leaves .6. While the holes II at the sides of the necks 9 may be formed so that the upper edges of the leaves are tangential there-' to, yet where the band 5 is quite narrow and it is undesirable to cut through too much of the band, the holes H at the sides of the necks 9 may be formed so that they extend into both the band and theleaves' I as shown in 1. The holes 0 i0 and H are provided to permit the necks to bend readily, to avoid having the necks or any portions of them extend outwardly beyond the edges of the band 5 when the expander is finished, and to prevent tearing at the metal at the hold.

It will also beiobserved here that the leaves I space the leaves 6 from the supportingband 5 and the necks 8 are bent on a pronounced radius thus reducing the strains and stresses placed on 40 these necks. The necks 9 have a shorter bend, but should one of them break it would not be particularly .serious since theoverlying leaf 6 would then hold its leaf 1 in position.

After the soft steel stamping is bent to shape in its final form the expander is heat-treated and v priately mounted in the piston ring groove.

The contacting ends l5 of the spring leaves 6 are slightly curved inwardly to avoid any likelihood of the sharp ends of the leaves digging into the piston ring. The gap in the expander band 5 is preferably diametrically opposite thejoint II in the piston ring.

By the use of the multiple or overlying springs 6 and l, I provide greater outward spring pressure or load against the piston ring in order to maintain the desired pressure of the piston ring against the cylinder wall. At the same time the under springs 1 cause the load or strain exerted on the leaves 6 to be more equally distributed throughout the length of the latter, as in operation the leaves flex or yield throughout their length instead of bending mainly from fulcrums' in line with the holes Ill. Thus, excessive localized strains are eliminated reducing the possibility of breakage.

In order to prevent relative movement between the expander and the piston ring, the inner surface of the ring at the ends thereof, next to the joint I1, is notched as at I9 providing shoulders approximately radial against which the ends of adjacent spring leaves 6 may abut as the ring and expander tend to rotate relative to each other. As shown in Fig. 2, an index hole 20 is provided in the band 5 and in assembling the expander and .ring this hole is to be placed behind the joint ll.

Fig. 5 shows a portion of a stamping from which a modified form of my expander may be made. It will be observed that the leaves 6 and 1 are of the same length and width and that the holes Ill and II are formed only in the band 5. The leaves 1 have notches 2| or recesses formed in their lower edges opposite the necks 9*. After the stamping is formed, the necks 9 are bent to place the leaves I against the band .5 and then necks 8 are bent to place the leaves 6 in overlying position with respect to the leaves P. The notches 2| are provided to accommodate the necks 8 which ,'engage or are located in the notches, the necks thus permitting the leaves I to be of the same width as the leaves 6 and the band 5 Furthermore, the engagement of each neck 8 in its appropriate notch would prevent longitudinal movement of its leaf 1 with respect to the band 5 should the neck 9 become broken. It will be observed that in this modified form, I have shown the leaves '1 to be of the same length as the leaves 6. In some instances it is not necessary to bow or curve the central portions of the leaves 6 and 1 of the finished expander, the leaves in that case being straight.

It is believed that the operation and advantages of my invention will be fully understood from the foregoing. It is also to be understood that while I have shown the preferred form of my invention other changes in detail and arrangement of parts may be made without departing from the spirit and scope of the invention as defined by the claims that follow.

I claim: a

l. A piston ring expander comprising a supporting band, a plurality of sets of superimposed spring leaves overlying and substantially concentric with the supporting band, the leaves of each set having portions in contact with each other, means connecting one edge of the outer leaves to said band, and means connecting one edge of the inner leaves to said band.

2. A piston ring expander comprising a supporting band, a plurality of sets of superimposed spring leaves overlying and substantially concentrio with the supporting band, the leaves of each set having portions in contact with each other," the outer leaves being longer and wider than the inner leaves, necks integrally connecting one edge of the band to one edge of the outer leaves, and 5 necks integrally connecting the other edge of the band to one edge of the inner leaves.

3. A spring steel piston ring expander comprising a supporting band, spring leaves, necks integrally connecting said spring leaves to saidlo band, and back spring leaves engaging said band. and first mentioned leaves and spacing the latter from said band.

4. A spring steel piston ring expander comprising a supporting band, front spring leaves over- 15 lying and substantially concentric with said band and spaced therefrom, necks integrally connecting one edge of said band with the central portion of one-edge of said leaves, and back spring leaves positioned between the band and said front 20 spring leaves and engaging the latter, the central portions of the back springs being in engagement with said band.

5. A spring steel piston ring expander comprising a. supporting band, front spring leaves over- 25 lying said band and spaced therefrom, necks integrally connecting one edge of said band with the central portion of one edge of said leaves, back spring leaves positioned between the band and said front spring leaves and engaging the 30 latter, the central portions of the back springs being in engagement with said band, and necks integrally connecting the opposite edge of said band with the central portion of one edge of said back leaves.

6. A resilient piston ring expander comprising a supporting band, a plurality of spring leaves, overlying and substantially concentric with said band, necks integrally connecting edges of said band and leaves, there being recesses in the band 40 at each side of each neck, the recesses being only in the band.

'7. A one-piece spring piston ringexpander, comprising a supporting band, and spring leaves integrally connected to said band at their central portions and having their end portions projecting in opposite directions therefrom, the supporting band also having spring portions underlying said spring leaves and contacting with the projecting portions of the leaves to augment the ex- 50 panding action of said leaves on a piston ring.

8. A resilient piston ring expander comprising a supporting band, a plurality of multiple spring leaves overlying the band, a neck integrally connecting one edge of the band to one edge of the outer leaf, and a second neck integrally connecting the other edge of the band to one edge of the inner leaf, the other edge of said inner leaf having a notch into which engages the neck of the outer leaf. r 9. A one-piece resilient piston ring expander comprising a supporting band, a plurality of sets of spring leaves overlying the band, necks integrally connecting one edge of the band to one edge of the outer leaves, and necks integrally connecting the other edge of the band to the adjacent edge of the innerleaves, the opposite edges of said inner leaves having notches into which en age the necks the outer leaves and the band and leaves being of the same width. 10. A spring ring expander comprising a thin flexible band and a plurality of sets of superimposed thin spring leaves resilient throughout their length and in overlying substantially concentric relation to said supporting band, the central portions of the leaves of each set being in direct contact with each other and the central portion of the innermost leaf being in direct contact with the supporting band, the total thickness of the expander at said portions being no greater than the combined thicknesses of the band and leaves, and means joining the central portions of the leaves to said hand without increasing the total thickness of the expander at said central portions.

11. A springring expander adapted to be used in a piston groove behind a piston ring, the expander comprising a thin flexible band substantially the width 01 the piston groove in which it is to be placed, and a plurality of sets of superimposed thin spring leaves resilient throughout their length and in overlying substantially concentric relation to said supporting band, the central portions of the leaves of each set being in direct contact with each other and the central portion of the innermost leaf being in direct contact with the supporting band, the total thickness of the expander at said portions being no reater than the combined thicknesses of the band and leaves, and means joining said central portions of the leaves to said band without increasing the total thickness of the expander 01 said central portions, and without increasing the width of the expander beyond the width of the band.

LEE M. BRANNAN. 

